The particles "wa", "o" and "ni" all come AFTER the noun. The sentence above translates to "I gave fish to Harold"

The particle wa is the topic marker. This is a foreign concept to English speaking people. Take this sentence, "Zou wa hana ga nagai desu." The topic is "zou", elephant. The particle ga shows that "hana", nose, is the subject of the sentence. The sentence roughly translates to "As for elephants, their noses are long." There is added confusion though. In the sentence "Watashi wa Ichiro desu" you would expect it to translate to "As for myself, am Ichiro" when in truth it means "I am Ichiro".